Field <field name> for target <target name> can be projected if IsDestinationNameDynamic is set to true in session properties.
The JMS target is configured to have a static destination name. When the destination name is static, the Integration Service uses the destination name from the application connection. You cannot project the destination name in the JMS target.
Enable IsDestinationNameDynamic in session properties, or remove the link to the destination in the JMS target.